Many devices which a person may ride upon have suspension systems that include springs and dampers. In some cases, such as for a skateboard, the suspension system is a part of an undercarriage assembly. In other cases, such as for a ski, the suspension system is built into the device or into a combination of devices (e.g., ski boot, wakeboard boot, snowboard boot). Some activities, such as skateboarding, snowboarding, skiing, wakeboarding, and the like may involve a rider taking high risks, resulting in appreciable impact to the riding device and, consequentially to the rider, when the suspension system of the riding device does not absorb all or an adequate amount impact.
Typically, an individual controls a riding device by shifting their weight and/or position to self-steer the riding device. In some activities, particularly when impact is not fully absorbed by the riding device, and the impact transmitted to the rider can cause at least momentary loss of control of the device or loss of balance, thereby potentially resulting in inability to steer the device or instability of the device. As a result, such a situation can lead to an injury of the rider.
For example, a skateboard, in particular, is prone to large shocks. It is common for a skateboard to be used in particularly adverse environments, such as jumps or flips at high speeds. Often, the impact on landing can be on the order of multiple G forces and, when the skateboard assembly does not absorb adequate quantities of forces, excessive force can be transmitted to the rider who can readily be injured. Further, the skateboard rider can often attempt multiple consecutive such techniques and if the impact from the first technique, such as a jump, is not absorbed, injuries can become even worse, since momentum of the rider is maintained in anticipation of a second technique. Therefore, it would be beneficial to create an undercarriage which improves shock absorbing.
In addition, the device itself may be damaged or have its useful life shortened if it does not absorb impact or stress adequately. Any of the board, the spring, the axle, the wheels, or other parts of the skate-board assembly may break either due to a particularly impactful event or a collection of events. If this were to happen, the rider can become seriously injured as well.
Thus, there is a need for a skateboard assembly that allows for absorption.
Another problem with known skateboards is durability. Because the undercarriage performs a less than ideal job at impact absorption, it is not uncommon for parts to break or crack. In particular, micro fractures readily develop and expand from impact to impact, leading to degraded board performance or even breakage.
In general, a skateboard typically includes an elongated platform that has a pair of truck assemblies mounted at opposite ends of its underside and opposed to one another, each with an axle and pair of wheels. Each truck assembly further incorporates a base plate secured to the platform and a pedestal. The assembly is used for propelling the skateboard somewhat along a path generally aligned with the skateboard's longitudinal axis. Each assembly further includes a pivot stem that projects radially outward from a mid-portion of the axle for seating in a recess formed in the base plate. A ring-shaped hanger also projects radially outward from a mid-portion of the axle, at a prescribed acute angle (e.g., 45 degrees) relative to the pivot stem, for engagement with a kingpin which projects downwardly from the base plate. In traditional truck assemblies, the kingpin is fixed in position. Upper and lower bushings secure the hanger around the kingpin.
Yet further assemblies include a pedestal which captures the nut that aligns and assembles the bushings and the primary tension bolt (the kingpin) through the skateboard truck and hanger assembly. The pedestal aids in assuring proper alignment, enabling easier removal and replacement of standard skateboard hardware, and preventing slippage of the mounting plate. The device also aids in absorbing shock and forces generated through the tension bolt sustained during a ride.
The assembly described briefly above is configured to enable a rider to steer the skateboard simply by shifting his/her weight distribution rightward or leftward on the skate-board platform. This weight shift causes the platform to tilt correspondingly relative to the axles of the two truck assemblies, which remain at all times level relative to the ground. The axles thereby are caused to pivot horizontally about the axes of their associated kingpins, which in turn causes the skateboard to steer rightward or leftward. Riders generally desire to steer the skateboard using very slight shifts in their weight distribution. Loose or slack bushings generally allow greater movement and steering of the ring-shaped hanger about the kingpin and thus are more responsive to slight weight shifts than are tight suspensions. However, loose or slack bushings can fail to prevent certain undesired ride characteristics.
One known skateboard suspension apparatus serves to deflect irregularities encountered by a skateboard's wheels and lower the center of gravity of the board while the board is in motion, thereby providing stability, but concurrently decreasing the turning radius. This device does not include a flexible spring.
Another known device includes a shock absorbing apparatus located between a base plate and a truck plate that is pivotally attached at one end of the assembly. When assembled onto a skateboard, the device absorbs shock through the suspension while concurrently allowing the rider to maintain steering control.